Paper screw cap



ug. 1945 c. w. soonwm 2,332,873

PAPER SCREW CAP 4 Filed Nov. 11, 1942 '3 Sheets-Sheet 1 INVENTOR. far![1. 60009120! I w g/m5) Aug. 14, 1945. c w GQQDwlN I 2,382,873

PAPER SCREW CAP Filed Nov. 11, 1942 3 Sheets-Sheet 2 7 INVENTQR. ("01"!Patented Aug. 14, 1945 PAPER SCREW CAP Carl W. Goodwin, NorthPlainfield, N .'J ass'ignor to American Seal-Kan Corporation ofDelaware, Wilmington, Del., a corporation of Delaware ApplicationNovember 11, 1942, Serial No. 465,194

7 Claims.

This invention relates to paper caps having an internal thread suitablefor use as screw-caps for jars, bottles and the like.

An object of the invention is to provide a threaded cap made from apaper blank or the like and having integrally formed threads of a higherdegree of hardness and rigidity than the remainder of the cap.

Another object is to provide a unitary cap of the above type which isformed from a paper blank by a die molding operation.

Another object is to provide a cap of the above type having integrallyformed solid, hard raised threads which are seamless in cross-section asdistinguished from being folded, laminated, or corrugated.

Another object is to provide a cap of the above type having outerreenforcing means to impart further rigidity thereto.

Another object is to provide a paper screw-cap having a sealing compoundfor eifecting an airtight seal with the lip of the bottle or jar towhich it is applied.

Variou other objects and advantages will be apparent as the nature ofthe invention is more fully disclosed.

Although the novel features which are characteristic of this inventionare set forth more in detail in the claims appended hereto, the natureand scope of the invention may be better understood by referring to thefollowing description, taken in connection with the accompanyingdrawings forming a part thereof, in which certain specific embodimentshave been set forth for purposes of illustration.

In the drawings: r

Fig. 1 is a vertical section through the upper die member embodying thepresent invention;

Fig. 1a is a vertical section through the lower die member embodying thepresent invention;

Fig. 2 is a transverse section taken on the line 2-2 of Fig. 1 showingthe internal die segments in contracted position;

Fig. 3 is a vertical section through'the upper and lower die members incap forming position;

Fig. 4 is a transverse section taken on the line 4-4 of Fig. 3 showingthe internal die segments in expanded position;

Figs. 5 to 8 are enlarged detail views showing successive operatingpositions of the forming dies;

. Fig. 9 isan inside perspective view of the finished cap;

Fig. 10 is an outside perspective View of the cap showing the. outerband being applied thereto;

Fig. 11 is a broken sectional view showing the cap applied to the mouthof a glass jar;

Fi 12 is a fragmentary plan view of the reenforcing cover;

Fig. 13 is a perspective view, partly in section, showing the cappositioned within a reenforcing shell; and y Fig. 14 is a perspectiveView partly in section showing a modified form of cap having aninternal'sealing compound for sealing the cap onto a bottle or jar. r I

In the following description and in the claims certain specific termsare used for conveniencein referring to the various details of theinvention. These terms, however, are to be interpreted as broadly as thestate of the art will permit,

In accordance with the present invention, the solid, raised threads of ahigh degree of hardness and rigidity are produced by die-forming aretreated paper blank under high'pressure. An essential characteristicresides in so pretreating the blanks that under the high pressuresemployed in die-forming, the fibers of the paper are broken down orre-arranged and are compactedand interfelted together to form a paperhaving a differ-- ent cross-section than the blank and which consists ofone solid, seamless, uniform, homogeneous layer as distinguished fromfolded or laminated layers which would be produced by merelyfolding theblank upon itself without causing a rearrangement of the fibers withinthe material.- The process may be considered to constitute paper weldingbecause the original contour lines and surfaces are destroyed and ahomogeneous section is produced which may be of a shape and thicknessdiifering from that of the original blank. In addition, the highpressure used in dieforming compacts the fibers to greatly increase thedensity and hardness of the paper. The threads may thus be made harderthan the remainder of the cap. This is an important feature since thethreads are relied upon for holding the cap inposition and are subjectedto the greatest stress.

The paper stock must be specially pretreated to condition the same forthe die-forming oper-. ation. This pretreatment comprises impregnatingthe paper with a composition with softens the fibers for forming butsets as a binder or stiffener for holding the fibers permanently informed position and imparts'increated rigidity thereto. A The paper may,for example, be imafiin .waxhaving incorporated therein a-small" amountof a hardening wax, such as carnauba or montan as set forth in BaumPatent No. 1,668,-

349, dated May 1, 1928. Moisture may be used if desired to assist insoftening the fibers. Other binder, hardening or water-proofingcompositions may also be used.

After the pre-treatment the paper is preferably allowed to stand for asubstantial period of time such, for example, as twenty-four hours, in aclosed container for seasoning and tempering.

It is then in condition for the die-forming oper ation.

A die for forming internally threaded paper covers for glass jars or thelike is shown in Figs.; 1 to 8. Referring first to Fig. la, the lowerdie is shown as comprising a base I having an axial bore through which aplunger 2 extends. The base carries an outer ring member 3 in which issecured, by means of screws 4, a stationary.

forming ring 5 which constitutes the outer forming member. The ring 5 isprovided with an inner peripheral surface 6 defining the outerperipheral surface of the cap skirt and an annular part! to form theouter portion of the cap diaphragm. Thesurface' 6 may be rounded as at6a to prevent injuring the paper as it is drawn thereover.

The plunger 2 carries a head 8 having a surface}! which, in its upperposition, is flush with the top surface 10 of the members 3 and 5Iasshown'in Fig. 1a and in its lower position is flush with the surface Iof the ring 5 as shown in Fig. 3. Thelplunger 2 is provided with aflange II which engages the base to limit its movement. A spring I2,seated in a bore |3 in the base I, bears against the head 8 and servesto hold the same normally in its upper position as shown in Fig. 1a...The inner surfacesfi and l of the ring 5 and the top surface 9 of thehead 8 conform to the outer surface of the finished cap.

The upper die is shown in Fig. 1 as comprising a housing in which aliner 2| and a spring 22 are seated. The liner 2| and the spring 22 areheld in positionby a cover 23 which is secured by screws 24. The spring22 bears against the surface 25 of a cup 26 having a ring 21 whichextends through an vopening in the end 28 of the housing 20 and having aflange 29 which is slidablexwithin the liner 2|. The end 28 of thehousing 20 engages the flange 29 to limit the movement of the cup 26.

.The housing 20 carries. a retaining ring 20 which is threaded thereonand in which a pressure ring 3| is positioned. This pressure ring 3| isfixedin the retaining ring 3|] by means of a spacer 32. A head 33 isslidably mounted within the retaining ring and carries a lip 34 whichslides within the spacer 32 and engages a shoulder 35 on the pressurering 3| for limiting the movement 'of the head 33.

A pin 40 is slidablymounted within thehead 33 and is provided with abottom flange 4| having a surface 42 conforming to the centralportion ofthe inner surface of the diaphragm of the cap. A plurality of segmentalmembers 45 are mounted for. radial sliding movement on the flange 4| andare normally held in their inner position by means of tension'springs46. These segmental members 45 are provided with bottom annular surfaces41 which conform to the outer portion. of the'inner surface of thediaphragm oft-the, cap and with peripheral surfaces 48 which formed inthe surfaces 48 to conform to the desired raised beads on the innersurface of the cap flange. The segmental members 45 are provided withshoulders 50 which are held against the flange 4| by means of a ring 5|bearing against the top surfaces of the members 45 and held downwardlyby springs 52 seated in recesses in the ring 5| and the head 33.

The springs 52, through the ring 5|, members 45 and flange 4|, alsoserve to hold the pin 40 in its lower position. The pin 40 is attachedto a top flange member 53 which slides in cooperating bores in the cup26 and in the head 33 and limits the relative movement of the pin 40with respect thereto. The head 33 is provided with a conical end surface54 which engages cooperating surfaces 55 on the members 45 to cam thesame outwardly.

The operation of the die is as follows. The springs 52 normally hold thesegmental members 45 and the post 40 in their lower position in whichthe members 45 are retracted by means of thetension springs 46 and thespring I2 holds head. 8 of the lower. diein its upper position as shownin Fig. la. A blank 60 is now positioned betweenthe dies and the diesare brought'together by either raising the lower die or lowering theupper die. As the diesapproach, the surfaces 42 and 41 of the flange 4|and of the segmental members 45 respectively first engage the top of theblank 60. The relationship between the various springs is such that oncontinued downward movement of the upper die the springs 52 arecompressed, thus lowering the head 33 with respect to the segmentalmembers 45 whereby the tapered surfaces 54 and 55 serve to expand thesegmental members 45 against the tension of the springs 46 into theposition shown in Fig. 5. The parts of the upper die now remain in thesame relative positions while the flange 4| and the segmental members 45press the head 8 down.. wardly against the. tension of the spring l2.

When the head 8 reaches the limit of its move-.

ment. with the bottom surface thereof engaging the surface of the basethe top surface 9 isin line with the annular surface I of the ring 5 asshown in Fig. 6. 7 This operation serves to cup the blank to form adiaphragm 62 and an upstandingmarginal flange or skirt 63. The innerperipheral surface 6 of the ring 5 and the outer peripheral surfaces 48of the segmental members 45 now define the contour of the finishedmarginal flange of the cap. The spacing between the surfacest and 48 isshown as greater than the thickness of the blank so that the flange 63rests loosely therein as shown in Fig. 6. Of course, if the flange ofthe cap is to be made of the same thickness-as the blank, the surfaces 6and 48 would'be-correspondingly spaced and the flange 63 would be snuglyheld thereby. g

. Furt er downward movement of the housing 20 compresses the sprin 22and permits the pressure ring 3| to move downwardly into the spacebetween the cooperating surfaces 6 and 43 first torearrange the fiberstqfill in the mold cavity as indicatedin Fig. '7 andthen to compact thesame to a hard, dense structure as shown in Fig. 8. 'During this stageof theoperation the fibers. are forced into the depressed threads 49 ofthe members 45 to formraised. threads 65 on the flange 64 of the formedcap. The entire flange,

64, including, the raised threads 65, is morehighly compacted and isthus harder and denser: than thediaphragm 66v of. the cap which hasabout the consistency of the originallblank. It is to beparticularlynoted that the threads and marginal flange are seamless, solid andhomogeneous as distinguished from being folded or laminated and have thecharacteristics of having been die-compressed from a pretreated, waxedblank.

When the die members are separated the reverse operation takes place,the pressure ring 3| first being raised, the cap lifted out of the lowerdie on the upper die and the segmental members 45 being retracted torelease the formed cap.

The formed cap, as shown in perspective in Fig. 9, is suitable for usewithout further treatment. In many cases, however, it is desirable toapply printing to the top for purposes of ornamentation or advertising.Such printing is preferably done on a thin paper cover which is securedby a suitable adhesive to the outer surface of the diaphragm 66 of thecap. For strengthening purposes, the cover 10 may be provided with tabsH which extend downwardly and are secured around the outside of theupstanding flange 64. These tabs may be contiguous to substantiallycompletely cover the outside of the skirt. In order to provide a morefinished appearance, and also to provide a further strengthening meansfor opposing the force which tends to cause the flange to spreadoutwardly when the cap is screwed tightly onto a bottle, a band ofstrengthening material such as tape or heavy paper 12 may then be woundaround the outer surface of the flange 64 over the tabs H. The cap thusproduced is sufliciently strong for most uses and has a pleasingfinished appearance.

In certain instances the caps may be used as a liner for a rigid outershell 80 as shown in Fig. 13. The outer shell may, for example, be madeof glass or other moldable material which is readily formed into cuppedshape with a top 8| and a downwardly extending flange 82. This assemblymay be made to possess the strength of a metal cap and may be used inmany instances as a replacement therefor. The paper liner may be held inthe shell by friction or may be adhesively secured therein as required.

According to a further embodiment of the invention, it is sometimesdesirable to provide an air-tight seal between the top of the jar orbottle and the inner surface of the cap. This may be accomplished asillustrated in Fig. 14 by recessing, if desired, a portion of the rim ofthe diaphragm 66 and inserting therein a sealing compound, preferably acompound having adhesive characteristics at room temperatures, such asanimal glue or plasticized thermoplastic materials, for example, ethylcellulose compounds or vinyl resins or the like. In certain instances athermoplastic material may be employed which must be heated to anelevated temperature for sealing purposes. This may be desirable incases where the seal must be maintained a long period of time.

The cap may include the usual disc liner of treated paper or othermaterial according to the contents of the container. This liner effectsa seal with the container lip and prevents the contents from coming intocontact with the cap itself.

It is to be understood that the above examples are only'illustrative andthat various changes and modifications may be made therein and that theinvention is capable of various uses which will be readily understood bya person skilled in the art.

What is claimed is:

1. A paper screw-cap comprising a central diaphragm portion and anupstanding annular skirt, said skirt having solid, raised screw threadsformed integrally on one face thereof, the opposite face beingsubstantially smooth, the paper in said skirt and threads containing abinder and being in a solid, homogeneous, seamless, interfeltedcondition, said skirt and threads being denser than the remainder of thecap and having a higher degree of hardness.

2. A paper screw-cap comprising a diaphragm portion and an upstandingannular skirt, said skirt being thicker than said diaphragm portion andhaving solid, raised screw thread formed integrally thereon, the paperin said skirt containing a binder and being in a solid, homogeneous,seamless, interfelted condition, said skirt and threads being denserthan the remainder of the cap and having a higher degree of hardness.

3. A paper screw-cap comprising a diaphragm portion and an upstandingannular skirt, said skirt being thicker than said diaphragm portion andhaving solid, raised screw threads formed integrally on the innerperipheral surface thereof and having a smooth, outer surface,the paperin said skirt containing a binder compound and being in a solid,homogeneous, seamless, interfelted condition, said skirt and threadsbeing denser than the remainder of the cap and having a higher degree ofhardness.

4. In a paper screw-cap as set forth in claim 1, a reenforcing bandsecured around the outside of said skirt to increase the rigiditythereof.

5. In a paper screw-cap as set forth in claim 1, a cover havingperipheral tabs extending doWn-, wardly over the outside of said skirtand adhesively secured thereto, said tabs being contiguous andsubstantially .covering the entire skirt, and a reenforcing band securedaround the outside of said skirt over said tabs to increase the rigiditythereof.

6. In a paper screw-cap as set forth in claim 1, an annularband ofadhesive material on the inner surface of said diaphragm to engage andseal against the lip of a container.

7. A paper screw-cap as set forth in claim 1 having an outer shell ofrigid material covering the entire outer surface of said diaphragm andskirt to impart a rigidity simulating that of a metal cap.

CARL W. GOODWIN.

